27 lines
536 B
Haskell
27 lines
536 B
Haskell
|
module ListUtils where
|
||
|
|
|
||
|
|
|
||
|
|
-- create a singleton list
|
||
|
|
--
|
||
|
|
singleton :: a -> [a]
|
||
|
|
singleton x = [x]
|
||
|
|
|
||
|
|
|
||
|
|
-- create a list of length n
|
||
|
|
--
|
||
|
|
--replicate :: Int -> a -> [a]
|
||
|
|
--replicate n x = take n (repeat x)
|
||
|
|
|
||
|
|
|
||
|
|
-- apply a function to the nth element of a list
|
||
|
|
--
|
||
|
|
onNth :: Int -> (a -> a) -> [a] -> [a]
|
||
|
|
-- onNth n f xs | n<1 = xs
|
||
|
|
-- onNth 1 f (x:xs) = f x:xs
|
||
|
|
-- onNth n f (x:xs) = x:onNth (n-1) f xs
|
||
|
|
|
||
|
|
onNth n f xs | n<1 = xs
|
||
|
|
onNth n f xs = case splitAt (n-1) xs of
|
||
|
|
(ys,[]) -> ys
|
||
|
|
(ys,z:zs') -> ys++f z:zs'
|